The present invention relates to a liquid container comprising an air chamber capable of storing a liquid entering an air open passage in a container body to be attached removably to a container attachment portion on an apparatus side.
Examples of a liquid container include an ink cartridge to be used in a printer of an ink jet type. In the ink cartridge for the printer of the ink jet type, an ink chamber accommodating an ink to be supplied to a print head is provided in a container body. The ink cartridge is removably fitted and attached to a cartridge attachment portion in a predetermined position in use. The ink accommodated in the ink chamber is supplied to the print head to be driven according to print data transferred from a host computer and is ejected onto a target position of a print medium, such as a paper, from a nozzle provided on the print head.
There have been proposed various ink cartridges of an air open type to be attached to the printer of the ink jet type, in which a container body to be attached removably to a cartridge attachment portion on the printer side includes an ink chamber for accommodating an ink, an ink supply hole provided in communication with the ink chamber and connectable to an ink receiving portion of the cartridge attachment portion, an air open passage for causing the ink chamber to communicate with an outside and introducing outside air into the ink chamber as the ink in the ink chamber is consumed, and an air chamber provided in a portion of the air open passage and capable of storing the ink entering the air open passage.
The air chamber is provided for preventing the ink from leaking out when the air in the ink chamber thermally expands due to a change in an ambient temperature and the ink in the ink chamber flows reversely in the air open passage by the thermal expansion of the air.
The air chamber for preventing the leakage of the ink is required to be devised in a connecting position to the air open passage in such a manner that a function of introducing the air into the ink chamber can be secured also when the cartridge is inclined, for example.
Moreover, it is also important to maintain a volume sufficient to accommodate the ink flowing reversely due to the thermal expansion of the air in the ink chamber, and thus a design is also required for maintaining the volume.
There has been proposed an ink cartridge comprising an air chamber that is provided independently in a lower position on the outside of the ink chamber and is caused to communicate with the ink chamber through a special air introducing path. Both side walls having a comparatively large area in the air chamber are formed by gas-liquid separation films which permit a passage of a gas and does not cause a liquid to pass (for example, see Patent Document 1).
Patent Document 1: JP-A-2004-209847 Publication
When the ink comes in contact with the gas-liquid separation film used for a partition wall of the air chamber, the passing property of the air is reduced in the contact area of the ink. For this reason, a gas permeability to the ink chamber is reduced more greatly than that in the beginning. As a result, there is a possibility that the reduction in the gas permeability to the ink chamber might prevent a smooth supply of the ink.
Furthermore, the gas-liquid separation film having a comparatively large area is caused to function as the partition wall on each of the ends of the air chamber. Therefore, it is necessary to employ a support structure for stably supporting the gas-liquid separation film like a flat wall. Consequently, an increase in components of the air chamber causes a deterioration in an assembling property and an increase in a cost.
Moreover, in a case in which the air chamber is provided on a printer side, it is necessary to air-tightly connect the air open passage between the printer and the ink cartridge, and therefore the formation of such a connection structure increases a cost.